The rise of the obesity epidemic

Findings from an IOE investigation into the body mass index (BMI) of over 56,000 Britons across five generations has informed government policy.

19 June 2017

By Ryan Bradshaw

Obesity presents a daunting public health challenge. Researchers from CLOSER, a consortium of leading UK longitudinal studies led by the IOE, looked at the body mass index (BMI) of more than 56,000 people born in the UK from 1946 to 2001. They found that children born since 1990 are up to three times more likely than older generations to be overweight or obese by age 10.

Longitudinal studies follow the same group of people through time, capturing information on all aspects of their lives. The UK is home to the largest and longest running portfolio of longitudinal studies anywhere in the world, several of which are based at the IOE. It is possible to track change across generations of Britons by comparing data both within and across studies.

CLOSER researchers compared measures of height, weight and BMI across five longitudinal studies:

MRC National Survey of Health and Development (1946 British birth cohort)

National Child Development Study (1958 British birth cohort)

1970 British Cohort Study

Avon Longitudinal Study of Parents and Children (Children of the 90s)

Millennium Cohort Study

This research is the first to track weight gain across multiple generations through much of their lives - from age 2 to 64 for the oldest participants.

Key findings

Since 1946, every generation has been heavier than the previous one - and it is the most overweight people who are becoming even heavier.

Children born since 1990 are up to three times more likely than older generations to be overweight or obese by age 10.

One in ten children born in 1946 were overweight or obese by age 11, compared to roughly one in four 11-year-olds today.

While childhood obesity is more prevalent among more recent generations, the majority of today’s children are still a normal weight.

Since 1946, every generation has been heavier than the previous one – and it is the most overweight people who are becoming even heavier. The heaviest 2 per cent of people born in 1946 had a BMI of around 20 by the age of 11, compared to around 27 for the most obese children born at the turn of the century.

People are becoming overweight or obese at an increasingly younger age. Half the men of the 1946 generation were overweight by the time they were 41, compared to age 30 for men born in 1970. Half the women born in 1946 were overweight by age 48, compared to 41 for the 1970 generation.

The more of their lives people spend overweight or obese, the greater their risk of developing chronic health conditions such as coronary heart disease, type 2 diabetes, high blood pressure and arthritis. The obesity ‘epidemic’ is projected to cost the UK’s National Health Service £22.9 billion per year by 2050.

While other UCL research has shown that losing weight at any point in adulthood can help reduce the risk, this study indicates that the UK needs to target its public health interventions at younger and younger ages in order to stem the spread of the obesity epidemic.

The obesity 'epidemic' is projected to cost the UK's National Health Service £22.9 billion per year by 2050.

The findings were cited in the Health & Social Care Information Centre’s Health Survey for England 2014 report, an influential report looking at changes in the health and lifestyles of people all over the country. They were also covered by NHS Choices, and subsequently taken up by Clinical Commissioning Groups, local Healthwatch groups and hospital trusts around the country.